1. Field of the Invention
The present invention relates to a porous elastic pavement material to be used for formation of an elastic pavement layer on a driveway or the like on which motor vehicles travel.
2. Description of the Related Art
For pavements such as driveways, footways and walkways in golf courses, elastic pavement materials are conventionally used for improvement of the shock absorbing property of road surfaces. Such an elastic pavement material typically includes granular rubber chips prepared by crushing waste tires, hard aggregates and a binder such as a urethane resin or an epoxy resin. The binder is present in the form of thin films on surfaces of the rubber chips, whereby the rubber chips are bound with one another or with the hard aggregates. Voids are present in the elastic pavement material. The voids and the elasticity of the rubber chips impart the elastic pavement material with a shock absorbing property and a noise reducing property. Particularly, where the elastic pavement material is used for the pavement of the driveway, the elasticity of the rubber chips suppresses impact sound and patterned vibration sound of vehicle tires generated by impacts occurring when the tires are brought into contact with the road surface. Further, air trapped between treads of the tires and the road surface is released through the voids, whereby noise such as air pumping sound of the tires generated during traveling of the motor vehicle is suppressed. Thus, traffic noise can be drastically reduced. In addition, the hard aggregates serve to cut a water film present between the tires and the surface of the elastic pavement layer when the road surface is wet in a rain, thereby effectively improving slip resistance in a wet state.
Fine hard aggregates are typically used as the hard aggregates in consideration of the elasticity and the noise reducing property of the pavement layer and the mixing compatibility with the binder. However, the fine hard aggregates distributed in the surface of the pavement layer are liable to be abraded away together with the binder, so that the rubber chips are partly exposed on the surface of the pavement layer. Therefore, the wet state slip resistance is reduced with time.
In order to sustain the effect of the hard aggregates for a prolonged period, an elastic pavement material is proposed which includes rubber chips containing hard aggregates dispersed therein (see, for example, JP-A-2005-2640).
However, a production process for the elastic pavement material disclosed in JP-A-2005-2640 is complicated with the need for preliminarily dispersing the hard aggregates in the rubber chips, thereby increasing the production costs.
In view of the foregoing, it is an object of the present invention to provide a porous elastic pavement material which is excellent in noise reducing effect and yet sustainably has a wet state slip resistance for a long period of time.